1. Field of the Invention
The present invention relates generally to modular electronic systems, and more particularly, to methods and systems for removably connecting modular electronic subsystems together.
2. Description of the Related Art
Many electronic products and systems include subsystems and subcomponents that must undergo validation testing and certification to ensure that the subsystem and subcomponent conforms to an established standard. One example of such a subsystem is a Bluetooth transceiver that can be used in any number of products (e.g., personal digital assistants, cellular telephones, computer keyboards, headsets, etc.). The Bluetooth technology is guided by an open specification for short-range wireless communication between electronic devices. A specific set of procedures has been defined by the Bluetooth Qualification Program (BQP) to minimize the interoperability problems among Bluetooth devices (e.g., Bluetooth transceivers). Each Bluetooth device must be tested to validate that the Bluetooth device is in compliance with the Bluetooth specifications. Other types of devices are governed by other specifications that must be validated. Bluetooth technology is an exemplary technology that must be validated; however, it should be understood that neither the present invention nor the problems described in the prior art are intended to be limited to Bluetooth technology or systems or devices that employ such technology that must be validated.
Validation of a Bluetooth device can be expensive in both time and financial commitments. The Bluetooth validation process requires third party testing to validate that the Bluetooth product meets the interoperability requirements (among several other aspects) required in the Bluetooth specification. Once the Bluetooth product has been so validated, the product is then certified by being registered with the Bluetooth organization.
The validation process is typically very time consuming and costly. Therefore repeating a product validation is something to be avoided if at all possible. One approach to avoiding repeated validation of a new device containing Bluetooth technology is to implement the Bluetooth device in a modular format. The modular Bluetooth device can then be validated. The validated, modular Bluetooth device can then be combined in any number of products without requiring each end product to be validated.
FIG. 1 is a top view of a typical Bluetooth module 100. The Bluetooth module 100 typically includes a printed circuit board (PCB) 102. A Bluetooth controller 104, RF devices 108A, 108B, and a flash memory 106 are surface mounted to the PCB 102. The flash memory 106 can store the Bluetooth protocol stack. An antenna 110 can also be surface mounted to the PCB 102.
Such Bluetooth modules are typically packaged in two formats. A first package format is packed as a multi-chip carrier (MCC), where the Bluetooth controller 104, flash memory 106, RF devices 108A, 108B and, optionally, some passive components, are assembled on the PCB 102 and then sealed in a ball grid array (BGA) package. The Bluetooth controller 104 and flash memory can also be stacked to reduce the area consumed by the device.
FIG. 2 shows a bottom side 112 of a typical MCC package. A set of land patterns 114 are provided on the bottom side 112 of the MCC package. For example, the land pattern 114 can be laid in an array on the bottom of the MCC package for making electrical contact to the main circuit board of the product that will include the validated, modular Bluetooth device. A more sophisticated MCC package includes solder balls attached to the land patterns to increase solderability.
A second package format includes surface-mounting the Bluetooth controller 104, flash memory 106, RF devices 108A, 108B and any optional passive components (e.g., antenna 110) on the top side of a PCB such as shown in FIG. 1 above. FIG. 3 shows a bottom side 112′ of another typical MCC package. The bottom side 112′ includes rows of land patterns 116 along the edge of the PCB 102 for mounting the Bluetooth module onto the main circuit board 128 of the product that will include the validated, modular Bluetooth device.
Electric signals are provided from the bottom edge of the PCB to the top layer, where all Bluetooth module components are populated. FIG. 4A is a detailed view of a portion of the edge of the PCB 102. To minimize the size of the validated, modular Bluetooth module, a half-cut, metal-plated via 126 is attached to each land pattern 116 from the edge of PCB 102.
FIG. 4B is a top view of validated, modular Bluetooth device 100 mounted to the main circuit board 128 of the product that will include the validated, modular Bluetooth device. The half-cut, metal-plated vias 126 provide additional area for solder connections 116″ to the main circuit board 128 of the product that will include the validated, modular Bluetooth device. In either of the package formats described in FIGS. 2-4B above, the validated, modular Bluetooth device 100 is typically soldered to the main circuit board 128.
One of the main problems of either modular Bluetooth module package format is that once the modular Bluetooth device 100 is soldered on the main circuit board 128, it is extremely difficult to remove without damaging one or both of the Bluetooth device and the main circuit board. Further, a Bluetooth device 100 that can be removable from the main circuit board 128 can be very useful. By way of example, during the evaluation stage where different types (e.g., manufacturers, models, etc.) of Bluetooth modules could be evaluated on the same main circuit board 128 for a direct performance comparison.
There are several removable solutions available for the Bluetooth module 100. FIG. 5A shows a main circuit board 138 of a product connected to a Bluetooth module 100′ with a Mictor connector 132. The Mictor connector 132 is mounted to the bottom side of Bluetooth module 100′. A properly chosen Mictor connector 132, for example a 38-pin version, can fit inside the board outline of a Bluetooth module 100′.
Unfortunately, the Mictor connector 132 is typically very small and not capable of providing sufficient mechanical support for the Bluetooth module 100′. As a result, additional mechanical support is typically required by adding supporting bar or supporting posts 136 and corresponding mounting holes near the opposite end of the Bluetooth module 100′ from the Mictor connector 132 to ensure the Bluetooth module can be securely attached to the main circuit board 138.
FIG. 5B shows a main circuit board 140 of another product connected to a Bluetooth module 100″ with a dual pin header 142. The dual pin header 142 is less costly and provides increased mechanical support as compared to a comparably sized Mictor connector 132. Supporting posts 136 can also be used with the dual pin header 142.
FIG. 5C shows another approach to provide a removable Bluetooth module 100 as a Bluetooth USB 150 dongle. The validated, modular Bluetooth module 100 is mounted on a PCB 152 that includes a USB connector 154 to form the Bluetooth USB dongle 150. The Bluetooth USB dongle 150 is a convenient solution to support the removability of the Bluetooth module 100.
Unfortunately, the Bluetooth USB dongle 150 can only be used with a main circuit board 156 of a product that includes a corresponding USB interface 158 that can connect to the USB connector 154. Many applications for the Bluetooth module 100 do not include a USB interface. By way of example, a typical micro-controller based embedded system typically does not include a USB interface. The Universal Asynchronous Receiver-Transmitter (UART) interface is more commonly used in such micro-controller based embedded systems.
In view of the foregoing, there is a need for an easy to use and inexpensive connection interface that provides sufficient mechanical support and allows the easy removability of a validated, modular Bluetooth device from a main circuit board of the product that will include the Bluetooth device.